Hallucinations in macular degeneration

The Fortean Times has an online article about the unusual experiences that can occur in a condition called macular degeneration, where light sensing cells in the part of the eye called the macular cease to work. As well as blindness in the central part of vision, hallucinations can occur.

“Hallucinations? What do you mean?” I asked, totally nonplussed. He outlined several forms of hallucination that were plaguing him. The first one to manifest was what Don described as looking like “a ball of string or basketwork, a globular shape with an aperture on one side”. He would see this image as if projected onto walls or other surfaces. He could sometimes make out a small face inside the aperture, and on the occasions when this became particularly evident the basket-like effect would adjust around it like a bizarre headdress.

This hallucinatory state is known as Charles Bonnet syndrome, after the 18th century philosopher who noticed the condition in his father.

Link to full article on http://www.forteantimes.com

Scientific American ‘Mind’ launches

Scientific American has launched a quarterly magazine on psychology and neuroscience called Scientific American Mind. I have the first issue in front of me which I just bought from the newsagent. It seems to be well put together and mercifully short on adverts, although isn’t cheap at 3.75ukp.

There’s some sample articles in full on the website and various bits and pieces that are worth checking out.

Link to SciAm Mind website.

Finding Geschwind’s territory

A new connection has been found between two of most important language areas in the brain. Broca’s area and Wernicke’s area have been linked to speech production and language comprehension respectively. They were some of the first discoveries that linked particular brain areas to specific mental abilities and are known to be joined by a bundle of neural fibres called the arcuate fasciculus.

Reseachers from London have now discovered that another parallel pathway connects the two areas, although it does not develop until about 5-7 years of age, suggesting that even quite major connections in the brain do not develop until well into childhood.

The pathway runs through an area they have named Geschwind’s territory after Norman Geshwind, the famous American neurologist who theorised that such a connection might exist.

Understanding the connectivity of the language areas is the brain is essential to the understanding and treatment of language problems after brain damage. These sorts of impairments are a common result of serious stroke or traumatic brain injury.

Link to story on newscientist.com.
Link to abstract from the Annals of Neurology.

The face, the brain and Marilyn Monroe

Researchers from London and Italy have just published a study on the brain areas involved in perceiving and understanding faces. They created an elegant experiment where they used morphing to compare how brain activity changes as a photograph is gradually blended from one person to another, for example, from Marilyn Monroe to Margaret Thatcher.

They found that the brain did not respond in the same gradual manner, and that activation shifted to specific areas at certain points in the blending process. When the blending was in its early stages, participants perceived the picture as the same person with physical changes to their face, an experience which caused activation in the inferior occipital gyrus. When the level of blending affected recognition of the pictured person, the right fusiform gyrus was activated, an area thought to be involved with judgements of familiarity for faces. When a participant was already familiar with the people in the pictures, the temporal lobes became active when the final face became clear. These areas have been linked to semantic memory and naming.

This study is important as it shows specialised areas of activation for different stages in the face perception process in a single experiment.

These stages have been hypothesised to exist for quite some time in a model developed by psychologists Vicki Bruce and Andy Young, largely from studies on people with prosopagnosia, a condition where face recognition can be impaired, usually after brain damage.

Link to BBC News story.
Link to story in The Guardian.
Link to abstract from Nature Neuroscience.

Hack #102 : Alter Input With Expectations

This is a hack which never made it into the book, but we thought it worth sharing. At this point, to get the most out of this hack, look at this figure (in a pop-up window) quickly before reading on. It’s not important to try and work out what it is, but have a good look. Seen it? Now, without further ado…

Hack #102: Alter Input With Expectation

feedback_thumb.png

The balance between feed-forward and feed-back connections in the brain gives a clue to the balance between raw sensation and expectations in constructing experience.

Feedback is ubiquitous in the brain. The brain is not just massively parallel [Hack #52], it is also massively interconnected- an awesomely complex cybernetic system.

Continue reading “Hack #102 : Alter Input With Expectations”

First week shouts

Our heroic contributor Alex Fradera has a nice way with some kind words about the book here

Suffice to say that if you want to know about the brain, and the mind, and you want a bunch of mavericks to illuminate it using cognitive and visual illusions, pop culture and web-references, wrapped up in a very chic, sleek simple design, you couldn’t go far wrong

Need To Know give us a mention too (cheers guys) and we got our first review at amazon.com which was four stars and said, amongst other things that the book is ‘unconventional in several ways’ – which i like!

Ghosts in the machine

Controversy has erupted over Michael Persinger’s findings that applying weak complex magnetic fields over the temporal lobes can induce unusual experiences, particularly the experience ‘sensing a presence’ in the room, which Persinger has linked to religious belief and spiritual experience.

This work was part of a larger project in which Persinger and his colleagues have reported strong links between temporal lobe disturbance and anomalous beliefs and experiences throughout the population.

However, a group of Swedish neuroscientists led by Pehr Granqvist have reported that they’ve failed to replicate Persinger’s results with magnetic stimulation when they used a double blind approach to running their experiments (where neither the experimentor nor the participant knows whether they are getting magnetic stimulation).

Persinger has replied by stating that the Swedish study was not an accurate replication.

Link to story on nature.com